class_docstr: Test to verify PruningSchedule behavior for step parameters.
  
  This is a parameterized test which runs over all PruningSchedule classes
  to ensure they validate parameters such as begin_step, end_step and frequency
  properly and also apply them correctly during execution.
code: def testBeginStepGreaterThanEqualsZero(self, schedule_type):
      with self.assertRaises(ValueError):
          self._construct_pruning_schedule(schedule_type, -1, 1000)
      with self.assertRaises(ValueError):
          self._construct_pruning_schedule(schedule_type, -5, 1000)
  
      self._construct_pruning_schedule(schedule_type, 0, 1000)
      self._construct_pruning_schedule(schedule_type, 1, 1000)
      self._construct_pruning_schedule(schedule_type, 100, 1000)
  
imports: from absl.testing import parameterized
  import tensorflow
  from tensorflow_model_optimization.python.core.keras import compat
  from tensorflow_model_optimization.python.core.quantization.keras import utils
  from tensorflow_model_optimization.python.core.sparsity.keras import pruning_schedule
label_desc: Use image node_id 2 for calling the PruningScheduleTest obj's underlying member method code with example usage: obj.testBeginStepGreaterThanEqualsZero(schedule_type) without return types